1. Field of the Invention
The present invention generally relates to optics and, more particularly, to lens barrel structures that are suitable for use with miniature cameras.
2. Related Art
Cameras often employ one or more lens elements to provide focusing or zooming features. Typically, the lens elements are located in a lens barrel that is positioned in proximity to an imager. Light received through the camera's aperture can be transmitted through the various lens elements of the lens barrel and focused on the imager.
In products such as digital cameras and other personal electronic devices, it is often important to utilize space and materials efficiently in order to allow the products to be miniaturized, as well as to reduce weight. As product sizes become smaller, efficient utilization of space and materials becomes increasingly important.
FIG. 1 illustrates a perspective view of a lens mount 420 engaging a lens barrel 110. FIG. 2 illustrates a cross-sectional side view of lens mount 420 separated from lens barrel 110. As illustrated, lens barrel 110 includes a housing 180. A plurality of lens elements 160 and a larger last lens element 170 are provided in lens barrel 180 and enclosed by housing 180. Housing 180 is sized of a substantially uniform diameter D1 which accommodates the largest lens within the barrel. Accordingly, diameter D1 is approximately equal to the diameter of last lens element 170.
Lens mount 420 has a ring portion 450 having an interior surface 490 as well as a substantially circular interior space 410. As illustrated, ring portion 450 has an exterior diameter D6 and an interior diameter approximately equal to diameter D1 of housing 180 of lens barrel 110. A plurality of threads 185 are provided on an external surface of housing 180 for engaging threads on interior surface 490 of lens mount 420. Raised portions 195 of housing 180 may be provided to secure housing 180 of lens barrel 110 against ring portion 450 after lens barrel 110 has been inserted into lens mount 420. Raised portions 195 may be provided on a right end of housing 180 (as illustrated in FIG. 2) or on a left end of housing 180 (not shown). As a result, lens barrel 110 may be inserted into lens mount 420 through interior space 410, allowing lens mount 420 to engage lens barrel 110 and secure lens barrel 110 to lens mount 420.
Unfortunately, lens barrel 110 fails to provide efficient utilization of space. In particular, although lens barrel 110 is sized with uniform diameter D1 to accommodate last lens element 170, it is nevertheless oversized with respect to lens elements 160. As a result, excess spaces 190 are formed between lens elements 160 and housing 180. These excess spaces 190 can cause exterior dimensions of lens barrel 110 and lens mount 420 to be unnecessarily large, resulting in less efficient utilization of space, and impeding the miniaturization of products in which lens barrel 110 is employed. Additional material may also be necessary to stabilize lens elements 160 within excess spaces 190, thereby contributing to excess weight.
Accordingly, there is a need for an improved approach to lens barrel design that overcomes the deficiencies discussed above. In particular, there is a need to provide an improved lens barrel design that provides efficient utilization of space and reduced weight when employed in miniature digital cameras and personal electronic devices.